1. Field of the Invention
The present invention relates to a negative film supplying device which successively supplies a plurality of rolls of negative film to a printing device.
2. Description of the Related Art
When developed negative films are exposed and are printed onto photographic printing paper, usually, the negative films are set at a negative carrier one at a time. A print operation key is operated, and printing light from a light source passes through the negative film so that the images on the negative film are exposed onto a photographic printing paper. Accordingly, when a plurality of negative films are successively printed, an operator must set the negative film and operate the print operation key each time a negative film is printed.
When a large number of negative films are to be printed successively, often the negative films are connected together by adhesive tape or the like so as to form one long strip of films which is wound on a reel. The reel is loaded in a printing device, and printing processing of all of the negative films is effected automatically. However, after printing, the connected films must be cut into individual units and collated with the printed prints. These processes may result in the negative film being damaged.
As a result, apparatuses have been proposed in which a plurality of negative films are superposed one on top of another and held, and the outermost negative film abuts a driving roller, and the negative films are successively conveyed by the driving force of the driving roller (e.g., U.S. Pat. No. 5,153,639). In this type of device, a plurality of negative films can be automatically and successively conveyed without the negative films being connected in a long strip, and the above-described drawback can be eliminated.
However, negative films are punched so that perforations are formed therein. Burrs, which can be seen if the negative film is examined very closely, exist at the peripheral edges of these perforations. As a result, when the negative films are superposed and only one roll thereof is to be conveyed, the burrs of one of the negative films catch with the burrs of negative films adjacent thereto, and unfortunately, a plurality of the negative films is conveyed simultaneously (multiple-conveying).
Further, when driving force is imparted to the outermost negative film of the superposed negative films, because the negative films contact each other, the friction coefficient thereof is large. Therefore, there are times when the negative films at an inner side of the outermost negative film are delivered simultaneously with the outermost negative film.
Moreover, when the holding of the negative film outside of the innermost negative film is canceled, i.e., when the negative film outside of the innermost negative film is released, the innermost negative film is pushed, especially at a portion thereof upstream of the holding member, due to the influence (the curving and the motion in the direction of thickness) of the rear portion of the negative film before the innermost negative film. Because there is no supporting member corresponding to the upstream portion of the innermost negative film which is pushed, a force opposing the holding force of the holding portion is applied to the innermost negative film, especially at a portion thereof downstream of the holding member, so that the innermost negative film is also released from the holding portion.